Thermal Trigger Lock for Fire Doors
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Solution Overview
Problem
Fire doors face challenges in maintaining their non-flammable properties during temperature variations, leading to deformation and inadequate fire-blocking capabilities, and existing locks do not automatically unlock during a fire, hindering their functionality.
Innovation Solution
A lock with a thermal trigger and biasing system that automatically releases the bolt from its locked position when a predetermined temperature is reached, allowing it to change positions between blocked and retracted configurations, ensuring the door can lock and unlock based on temperature thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bolt is blocked in the retracted position to facilitate daily use, then ease of operation is improved, but reliability deteriorates because the door cannot block fire effectively
Solution Approach 1:
The lock is configured in advance with the bolt blocked in the retracted position for easy daily operation. The thermal trigger mechanism is pre-set to automatically detect temperature rise and release the bolt from blocking when fire conditions occur, transforming the bolt to the protruding position to block the fire door. This preliminary configuration allows the system to maintain ease of operation while ensuring fire-blocking reliability through automatic activation.
2Reliability
If the door is kept locked to prevent unauthorized entry, then security is improved, but reliability deteriorates because the door prevents emergency services from entering during fire
Solution Approach 1:
The lock system monitors temperature as a critical parameter and automatically changes its state based on temperature thresholds. During normal conditions, the door remains locked for security. When the temperature rises to indicate fire conditions, the thermal trigger activates and changes the bolt position from locked to unlocked, allowing emergency services to enter. This parameter-based state change resolves the contradiction between security and emergency access.
Solution Approach 2:
The thermal trigger mechanism converts the harmful effect of heat (which would normally indicate a dangerous fire condition) into a beneficial automatic unlocking function. The heat detected during fire conditions activates the thermal trigger, which releases the bolt and unlocks the door, transforming the harmful thermal energy into a life-saving automatic emergency release mechanism.
3Reliability
If the door material is made non-flammable to prevent fire spread, then fire resistance is improved, but shape deteriorates due to warping under high temperature
Solution Approach 1:
The locking function is extracted from the door structure itself and placed into a separate thermal-triggered lock mechanism. This allows the door to be made of non-flammable materials for fire resistance while the separate lock system, equipped with the thermal trigger, automatically responds to temperature changes. The extracted locking mechanism can reliably detect thermal conditions and actuate without being constrained by the door material's thermal deformation characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The lock enables easy daily use while ensuring the door remains locked during normal conditions and automatically unlocks to prevent fire spread when temperatures rise, maintaining its fire-blocking role without deformation.
Implementation Method 1
Due to their non-flammable characteristics, fire doors are subject to significant temperature variations in the event of a fire. Indeed, in a few fifteen minutes, the temperature of the environment of the door goes from ambient temperature to several hundred degrees Celsius, of the order of 900°C. Thus, these gates are known to warp.
Implementation Method 2
a system for biasing the bolt in translation then driving the bolt in translation as well released
Data Source
Figure 1
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Figure 3
AI summary
The lock (1) comprises a housing (2) containing a bolt (3), and an opening (0) through which the bolt can move, at least between a protruding locked position and a retracted double-locked position. The lock includes a thermal trigger (8) inside the housing which, at a threshold temperature, releases the bolt from its locked position. A bolt translation system (9) then moves the released bolt. The bolt has one notch for each locked position, and the lock includes a lever (6) comprising a protruding finger (7) adapted to engage with notches (4, 5) of the bolt to lock it in one of the locked positions, the bolt being released by retraction of the finger when the thermal trigger reaches the threshold temperature.